Action Synopsis: Bee Conservation About Actions

Provide set-aside areas in farmland

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

Two replicated trials showed that species richness of bees nesting (one study) or foraging (one study), is higher on set-aside that is annually mown and left to naturally regenerate for two years or more, relative to other set-aside management regimes or, in the nesting study, to arable crop fields.


About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled trial with four replicates of each treatment (Gathmann et al.1994) compared cavity-nesting bees and wasps nesting on set-aside arable land managed in six different ways with crop fields and old meadows in Kraichgau, southwest Germany. The study used reed Phragmites australis stem nest boxes (described in 'Provide artificial nest sites for solitary bees'), and recorded nesting only, not foraging activity. Set-aside fields were either sown in the year of study, with a grass-clover mix or phacelia Phacelia tanacetifolia (also known as scorpion weed, lacy phacelia or tansy phacelia)or were in their first or second year of natural regeneration, with or without mowing. Overall, naturally regenerated fields had significantly more nests, and more nesting species than fields sown with fallow or arable crops. Of the six set-aside treatments, the most species were found on two-year-old set-aside, mown in late June or early July, with a total of eight nesting bee species. This compares with four bee species found on 1-year-old unmown set-aside, and none on set-aside sown with phacelia. Twelve bee species were found on old meadows (>30 years old, with old fruit trees). Amongst 2-year-old, naturally regenerated set-aside fields, mown fields had more than twice as many species (bees and wasps) as unmown fields (average 4.8 species/field vs. 1.8).

    Study and other actions tested
  2. A second replicated trial in the same region (Steffan-Dewenter & Tscharntke 2001) examined the abundance and species richness of foraging bees, both solitary and social, on annually mown set-aside fields of different ages and management. The number of bee species increased with the age of set-aside fields, from 15 species on 1-year-old fields to 25 species on 5-year-old fields. Two-year-old set-aside fields had the most bee species - 29 on average, compared to 32 species for old meadows, including an average of around five oligolectic species (specialising on pollen from a small group of plant species). One-year-old set-aside fields sown with phaceliahad an average of 13 bee species, mainly common, generalised species of bumblebee Bombus and Lasioglossum.

    Study and other actions tested
Please cite as:

Dicks, L.V., Showler, D.A. & Sutherland, W.J. (2010) Bee conservation: evidence for the effects of interventions. Pelagic Publishing, Exeter, UK


Where has this evidence come from?

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Bee Conservation

This Action forms part of the Action Synopsis:

Bee Conservation
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